Neomycin, but Not Neamine, Blocks Angiogenic Factor Induced Nitric Oxide Release through Inhibition of Akt Phosphorylation

Angiogenesis, the growth of new blood vessels, is a critical factor of carcinogenesis. Neomycin and neamine, two drugs blocking the nuclear translocation of angiogenin (ANG), have been proven to inhibit tumour growth in vivo. However, the high toxicity of neomycin prevents its therapeutic use, thus indicating that the less toxic neamine may be a better candidate. Endothelial cells were cultured on a biocompatible multiple microelectrode array (MMA). The release of NO evoked by ANG or vascular endothelial growth factor (VEGF) was detected electrochemically. The effects of neomycin and neamine on ANG- and VEGF-induced NO releases have been investigated. Neomycin totally blocks NO release for concentrations down to the pM range, probably through the inhibition of the Akt kinase phosphorylation, as revealed by confocal microscopy. On the other hand, both ANG- and VEGF-induced NO releases were not significantly hindered by the presence of high concentrations of neamine. The inhibition of the Akt pathway and NO release are expected to lead to a severe decrease in tissue growth and repair, thus indicating a possible cause for the toxicity of neomycin. Furthermore, the data presented here show that ANG- and VEGF-induced NO releases are not dependent on the nuclear translocation of angiogenin, as these events were not abolished by the presence of neamine.

Analysis of ribonuclease activity in sub-nanoliter droplets by label-free fluorescence measurements

We report the results of a label-free analysis of ribonuclease activity using droplet-based microfluidics.

Ribonuclease 5 coordinates signals for the regulation of intraocular pressure and inhibits neural apoptosis as a novel multi-functional anti-glaucomatous strategy

Glaucoma is a vision-threatening disorder characterized by progressive death of retinal ganglion cells (RGCs), although little is known about therapeutic milestones. Due to its complex and multifactorial pathogenesis, multipronged therapeutic approach is needed. Angiogenin (ANG), now called ribonuclease (RNase) 5, has been previously known as angiogenic factor and more recently its biologic activity is extended to promoting cell survival via its ribonucleolytic activity. Here, we revealed the defect of ANG in human glaucomatous trabecular meshwork (TM) cells and identified novel multiple functions of ANG as an anti-glaucomatous strategy. ANG was highly expressed in normal eyes and normal TM cells compared to glaucomatous TM cells. ANG induced intraocular pressure (IOP) lowering in rat models of both normal and elevated IOP, and as a possible mechanism, activated Akt-mediated signals for nitric oxide (NO) production, an important regulator of IOP in glaucomatous TM cell. Moreover, we demonstrated ANG-induced production of matrix metalloproteinase (MMP)-1 and -3 and rho-kinase inhibition for TM remodeling. For anti-glaucomatous defense optimization, ANG not only elicited immune-modulative pathways via indolamine 2,3-dioxygenase (IDO) activation in TM cells and suppression of Jurkat T cells, but also rescued neural stem cells (NSCs) from apoptosis induced by glaucomatous stress. These results demonstrate that novel multi-functional effects of ANG may have benefits against glaucoma in ocular tissues.

The dual binding site of angiogenin and its inhibition mechanism: the crystal structure of the rat angiogenin-heparin complex

The heparin complex of rat angiogenin revealed that a heparin strand is fitted into a positively charged groove formed by the dual binding site of rat angiogenin, suggesting that cell adhesion to angiogenin is facilitated by its interaction with substrates on the cell surface and can be inhibited by heparin.

Real-time analysis of diaquat dibromide monohydrate in water with a SERS-based integrated microdroplet sensor

We report the fast and sensitive trace analysis of diaquat dibromide monohydrate (DQ) in water using a surface-enhanced Raman scattering (SERS)-based microdroplet sensor. This sensor is composed of two compartments: the first one is for droplet generation for fresh silver nanoparticle (AgNP) synthesis and the second for droplet merging for SERS detection. Silver ions were nucleated and grown to large size AgNPs in droplets, and then each droplet was synchronously merged with another droplet containing DQ for SERS detection. This two-phase liquid-liquid segmented flow system prevented memory effects caused by the precipitation of nanoparticle aggregates on channel walls because the aqueous droplets were isolated by a continuous oil phase. The limit of detection (LOD) of DQ in water was determined to be below 5 nM, which satisfies the maximum contaminant level defined by the United States EPA. This method was also validated successfully in DQ-spiked tap water. The SERS-based integrated sensing system is expected to be useful as an in-the-field sensing platform for fast and reproducible trace analysis of environmental pollutants in water.

Integration of monolithic porous polymer with droplet-based microfluidics on a chip for nano/picoliter volume sample analysis

In this paper, a porous polymer nanostructure has been integrated with droplet-based microfluidics in a single planar format. Monolithic porous polymer (MPP) was formed selectively within a microfluidic channel. The resulting analyte bands were sequentially comartmentalised into droplets. This device reduces band broadening and the effects of post-column dead volume by the combination of the two techniques. Moreover it offers the precise control of nano/picoliter volume samples.

Integrated pneumatic micro-pumps for high-throughput droplet-based microfluidics

Droplet-based microfluidic systems have recently emerged as powerful experimental tools in the chemical and biological sciences.

Droplet-Based Microfluidics

Over the past two decades, the application of microengineered systems in the chemical and biological sciences has transformed the way in which high-throughput experimentation is performed. The ability to fabricate complex microfluidic architectures has allowed scientists to create new experimental formats for processing ultra-small analytical volumes in short periods and with high efficiency. The development of such microfluidic systems has been driven by a range of fundamental features that accompany miniaturization. These include the ability to handle small sample volumes, ultra-low fabrication costs, reduced analysis times, enhanced operational flexibility, facile automation, and the ability to integrate functional components within complex analytical schemes. Herein we discuss the impact of microfluidics in the area of high-throughput screening and drug discovery and highlight some of the most pertinent studies in the recent literature.

SERS-based immunoassay of tumor marker VEGF using DNA aptamers and silica-encapsulated hollow gold nanospheres

A novel SERS-based sandwich immunoassay using DNA aptamers, silica-encapsulated hollow gold nanospheres (SEHGNs) and a gold-patterned microarray was developed for sensitive detection of VEGF (vascular endothelial growth factor) angiogenesis protein markers. Here, a DNA aptamer conjugated to SEHGN was used as a highly reproducible SERS-encoding nanoprobe, and a hybrid microarray including hydrophilic gold wells and other hydrophobic areas was used as a SERS substrate. Target specific DNA aptamers that fold into a G-quadruplex structure were used as a target recognition unit instead of VEGF antibodies. The detection sensitivity was increased by 2 or 3 orders of magnitude over the conventional ELISA method. In particular, the dynamic concentration range was 3 or 4 orders of magnitude greater than that of conventional ELISA. The results demonstrate that this sensing strategy using DNA aptamers is a powerful platform for the design of novel immune-sensors with high performance. In particular, SERS-based detection using SEHGNs provides great promise for highly sensitive biomarker sensing with unprecedented advantages.

Trace analysis of mercury(II) ions using aptamer-modified Au/Ag core-shell nanoparticles and SERS spectroscopy in a microdroplet channel

We report the rapid and highly sensitive trace analysis of mercury(ii) ions in water using a surface-enhanced Raman scattering (SERS)-based microdroplet sensor. Aptamer-modified Au/Ag core-shell nanoparticles have been fabricated and utilized as highly functional sensing probes. All detection processes for the reaction between mercury(II) ions and aptamer-modified nanoparticles were performed in a specially designed microdroplet channel. Small water droplets that included sample reagents were separated from each other by an oil phase that continuously flowed along the channel. This two-phase liquid-liquid segmented flow system prevented the adsorption of aggregated colloids to the channel walls due to localized reagents within encapsulated droplets. The result was reduced residence time distributions. The limit of detection (LOD) of mercury(II) ions in water was determined by the SERS-based microdroplet sensor to be below 10 pM, which is three orders below the EPA-defined maximum contaminant level. This combination of a SERS-based microfluidic sensor with aptamer-based functional nanoprobes can be used for in-the-field sensing platforms, due to its size and simplicity.

Simultaneous detection of duplex DNA oligonucleotides using a SERS-based micro-network gradient chip

We report the development of a programmable surface-enhanced Raman scattering (SERS)-based micro-network gradient platform to simultaneously detect two different types of DNA oligomer mixtures. The utility of this platform was demonstrated by quantitative analysis of two breast cancer-related (BRCA1) DNA oligomer mixtures. To generate on-demand concentration gradients, the microfluidic circuit was designed using an electric-hydraulic analogy. Then a multi-gradient microfluidic channel was fabricated based on the theoretical design of the concentration control module. These micro-network structures automatically produce a series of different concentration gradients by continuously mixing Cy3-labeled DNA oligomers (BRAC1-Mutation) with TAMRA-labeled DNA oligomer (BRAC1-Wild). The SERS signals for different ratios of duplex DNA oligomer mixtures, adsorbed on the surface of silver nanoparticles, were measured under flowing conditions. Total analysis time from serial mixing to SERS detection takes less than 10 min because all experimental conditions are automatically controlled inside the exquisitely designed microfluidic channel. This novel SERS-based DNA sensing technology in a micro-network gradient channel is expected to be a powerful analytical tool to simultaneously detect multiple DNA oligomer mixtures.

Human apolipoprotein(a) kringle V inhibits ischemia-induced retinal neovascularization via suppression of fibronectin-mediated angiogenesis

Retinal neovascularization is observed in progression of diabetic retinopathy. New vessels grow into the vitreous cavity in proliferative diabetic retinopathy, resulting in traction retinal detachment and vitreous hemorrhage. To overcome the catastrophic visual loss due to these complications, efforts have been focused on the treatment of retinal neovascularization. In this study, we demonstrated the inhibitory effect of recombinant human apolipoprotein(a) kringle V (rhLK8) in an animal model of ischemia-induced retinal neovascularization. rhLK8 induced no definite toxicity on endothelial cells and retinal tissues at the therapeutic dosage. Interestingly, rhLK8 showed antiangiogenic effect, particularly on fibronectin-mediated migration of endothelial cells. Further experiments demonstrated high binding affinity of rhLK8 to α3β1 integrin, and suppression of it might be the mechanism of antiangiogenic effect of rhLK8. Furthermore, rhLK8 inhibited phosphorylation of focal adhesion kinase, resulting in suppression of activation of consequent p130CAS-Jun NH(2)-terminal kinase. Taken together, our data suggested the possible application of rhLK8 in the treatment of retinal neovascularization by suppression of fibronectin-mediated angiogenesis.

Fabrication of SERS-fluorescence dual modal nanoprobes and application to multiplex cancer cell imaging

We report a highly sensitive optical imaging technology using surface-enhanced Raman scattering (SERS)-fluorescence dual modal nanoprobes (DMNPs). Fluorescence microscopy is a well-known imaging technique that shows specific protein distributions within cells. However, most currently available fluorescent organic dyes have relatively weak emission intensities and are rapidly photo-bleached. Thus more sensitive and stable probes are needed. In this work we develop DMNPs, which can be used for both SERS and fluorescence detection. SERS detection is a powerful technique that allows ultrasensitive chemical or biochemical analysis through unlimited multiplexing and single molecule sensitivity. Combining advantages of fluorescence and SERS allows these dual modal nanostructures to be used as powerful probes for novel biomedical imaging. In this work, the fabrication and characterization of the SERS-fluorescence DMNPs and application to biological imaging were investigated using markers CD24 and CD44, which are co-expressed in MDA-MB-231 breast cancer cells, as a model system. SERS imaging with DMNPs was found to be a powerful tool to determine the co-localization of CD24 and CD44 in the cell.

Fluorescence detection methods for microfluidic droplet platforms

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that accompany system miniaturisation. Advantages include the ability to efficiently process nano- to femoto- liter volumes of sample, facile integration of functional components, an intrinsic predisposition towards large-scale multiplexing, enhanced analytical throughput, improved control and reduced instrumental footprints. In recent years much interest has focussed on the development of droplet-based (or segmented flow) microfluidic systems and their potential as platforms in high-throughput experimentation. Here water-in-oil emulsions are made to spontaneously form in microfluidic channels as a result of capillary instabilities between the two immiscible phases. Importantly, microdroplets of precisely defined volumes and compositions can be generated at frequencies of several kHz. Furthermore, by encapsulating reagents of interest within isolated compartments separated by a continuous immiscible phase, both sample cross-talk and dispersion (diffusion- and Taylor-based) can be eliminated, which leads to minimal cross-contamination and the ability to time analytical processes with great accuracy. Additionally, since there is no contact between the contents of the droplets and the channel walls (which are wetted by the continuous phase) absorption and loss of reagents on the channel walls is prevented. Once droplets of this kind have been generated and processed, it is necessary to extract the required analytical information. In this respect the detection method of choice should be rapid, provide high-sensitivity and low limits of detection, be applicable to a range of molecular species, be non-destructive and be able to be integrated with microfluidic devices in a facile manner. To address this need we have developed a suite of experimental tools and protocols that enable the extraction of large amounts of photophysical information from small-volume environments, and are applicable to the analysis of a wide range of physical, chemical and biological parameters. Herein two examples of these methods are presented and applied to the detection of single cells and the mapping of mixing processes inside picoliter-volume droplets. We report the entire experimental process including microfluidic chip fabrication, the optical setup and the process of droplet generation and detection.

Thermoset polyester droplet-based microfluidic devices for high frequency generation

The vast majority of droplet-based microfluidic devices are made from polydimethylsiloxane (PDMS). Unfortunately PDMS is not suitable for high frequency droplet generation at high operating pressure due to its low shear modulus. In this paper, we report the fabrication and testing of microfluidic devices using thermoset polyester (TPE). The optical characteristics of the fabricated devices were assessed and substrate resistance to pressure also investigated. TPE devices bonded using an O(2) plasma treated PET substrate at 76 °C were shown to function efficiently at pressures up to 18 MPa. TPE material retains many of the attractive features of PDMS such as ease of fabrication but significantly, has superior mechanical properties. The improved resistance of TPE to high pressures enabled investigation of high frequency droplet generation as a function of a wide range of flow-rates with three different oils as continuous phase.

An electrochemical functional assay for the sensing of nitric oxide release induced by angiogenic factors

Nitric oxide (NO) is a critical biological mediator involved in numerous diseases. However, the short lifetime of this molecule in biological conditions can make its study in situ complicated. Here, we review some recent results on the role of NO in angiogenesis, obtained using a biocompatible microelectrode array. This simple system allowed for the quick and easy quantification of NO released from cells grown directly on the surface of the sensor. We have used this technology to demonstrate that angiogenin induces NO release, and to partially elucidate its intracellular transduction pathway.

Pharmacoproteomic analysis of a novel cell-permeable peptide inhibitor of tumor-induced angiogenesis

P11, a novel peptide ligand containing a PDZ-binding motif (Ser-Asp-Val) with high affinity to integrin α(v)β(3) was identified from a hexapeptide library (PS-SPCL) using a protein microarray chip-based screening system. Here, we investigated the inhibitory mechanism of P11 (HSDVHK) on tumor-induced angiogenesis via a pharmacoproteomic approach. P11 was rapidly internalized by, human umbilical vein endothelial cells (HUVECs) via an integrin α(v)β(3)-mediated event. Caveolin and clathrin appeared to be involved in the P11 uptake process. The cell-penetrating P11 resulted in suppression of bFGF-induced HUVEC proliferation in a dose-dependent manner. Phosphorylation of extracellular-signal regulated kinase (ERK1/2) and mitogen-activated protein kinase kinase (MEK) in bFGF-stimulated HUVECs was inhibited by cell-permeable P11. Proteomic analysis via antibody microarray showed up-regulation of p53 in P11-treated HUVECs, resulting in induction of apoptosis via activation of caspases-3, -8, and -9. Several lines of experimental evidence strongly suggest that the molecular mechanism of P11, a novel anti-angiogenic agent, inhibits bFGF-induced HUVEC proliferation via mitogen-activated protein kinase kinase and extracellular-signal regulated kinase inhibition as well as p53-mediated apoptosis related with activation of caspases.

Highly reproducible immunoassay of cancer markers on a gold-patterned microarray chip using surface-enhanced Raman scattering imaging

This paper reports a highly reproducible immunoassay of cancer markers using surface-enhanced Raman scattering (SERS) imaging. SERS is a highly sensitive detection method but it is limited in its ability to achieve reproducible signal enhancement because of the difficulty with precisely controlling the uniform distribution of hot junctions. Consequently, inconsistent enhancement prevents the wide exploitation of SERS detection as a bio-detection tool for quantitative analysis. To resolve this problem, we explored the use of a SERS imaging-based immunoassay. For this purpose, Raman reporter-labeled hollow gold nanospheres (HGNs), were manufactured and antibodies were immobilized onto their surfaces for targeting specific antigens. After the formation of sandwich immunocomplexes using these functional HGNs on the surfaces of gold patterned wells, the SERS mapping images were measured. For target protein markers, 12×9 pixels were imaged using a Raman mapping technique in the 0-10(-4) g/mL concentration range, and the SERS signals for 66 pixels were averaged. Here, the SERS imaging-based assay shows much better correlations between concentration and intensity than does the conventional point-based assay. The limits of detection were determined to be 0.1 pg/mL and 1.0 pg/mL for angiogenin (ANG) and alpha-fetoprotein (AFP), respectively. This detection sensitivity is increased by three or four orders of magnitude over that of conventional ELISA method. The detectable dynamic range for SERS imaging (10(-4)-10(-12) g/mL) is also much wider than that for ELISA (10(-6)-10(-9) g/mL).

Inhibitory effect of salmosin, a Korean snake venomderived disintegrin, on the integrin αv-mediated proliferation of SK-Mel-2 human melanoma cells

We have investigated the inhibitory effect of salmosin on integrin-mediated human tumour cell proliferation. SK-Mel-2 human melanoma cell adhesion to denatured collagen or vitronectin was found to be significantly and statistically inhibited by salmosin in a dose-dependent manner (P < 0.05). Moreover, the binding of SK-Mel-2 cells to salmosin-coated plates was specifically disrupted by anti-integrin αv monoclonal antibody at 8αg mL−1, but not by anti-integrin monoclonal antibody. These findings indicated that salmosin inhibited the adhesion of SK-Mel-2 cells to denatured collagen by specifically blocking integrin αv. The proliferation of SK-Mel-2 cells on a denatured collagen-coated plate was statistically and significantly inhibited by salmosin induced apoptosis in a dose-dependent manner (P < 0.05). Anti-integrin αv monoclonal antibody, anti-integrin αvβ3 monoclonal antibody, and synthetic RGD peptide also suppressed SK-Mel-2 cell proliferation. Several lines of experimental evidence strongly suggested that the inhibition of SK-Mel-2 cell proliferation by salmosin was due to the induction of apoptosis via the blocking of integrin αv-mediated cell survival.

Ribonuclease inhibitor regulates neovascularization by human angiogenin

Human angiogenin (ANG) is a homologue of bovine pancreatic ribonuclease (RNase A) that induces neovascularization. ANG is the only human angiogenic factor that possesses ribonucleolytic activity. To stimulate blood vessel growth, ANG must be transported to the nucleus and must retain its catalytic activity. Like other mammalian homologues of RNase A, ANG forms a femtomolar complex with the cytosolic ribonuclease inhibitor protein (RI). To determine whether RI affects ANG-induced angiogenesis, we created G85R/G86R ANG, which possesses 10(6)-fold lower affinity for RI but retains wild-type ribonucleolytic activity. The neovascularization of rabbit corneas by G85R/G86R ANG was more pronounced and more rapid than by wild-type ANG. These findings provide the first direct evidence that RI serves to regulate the biological activity of ANG in vivo.

A novel integrin alpha5beta1 antagonistic peptide, A5-1, screened by Protein Chip system as a potent angiogenesis inhibitor

Integrin alpha5beta1 immobilized on a ProteoChip was used to screen new antagonistic peptides from multiple hexapeptide sub-libraries of the positional scanning synthetic peptide combinatorial library (PS-SPCL). The integrin alpha5beta1-Fibronectin interaction was demonstrated on the chip. A novel peptide ligand, A5-1 (VILVLF), with high affinity to integrin alpha5beta1 was identified from the hexapeptide libraries with this chip-based screening method on the basis of a competitive inhibition assay. A5-1 inhibits the integrin-fibronectin interaction in a dose-dependent manner (IC(50); 1.56+/-0.28 microM. In addition, it inhibits human umbilical vein endothelial cell proliferation, migration, adhesion, tubular network formation, and bFGF-induced neovascularization in a chick chorioallantoic membrane. These results suggest that A5-1 will be a potent inhibitor of neovascularization.

Cancer gene therapy using adeno-associated virus vectors

Gene therapy has offered highly possible promises for treatment of cancers, as many potential therapeutic genes involved in regulation of molecular processes may be introduced by gene transfer, which can arrest angiogenesis, tumor growth, invasion, metastasis, and/or can stimulate the immune response against tumors. Therefore, viral and non-viral gene delivery systems have been developed to establish an ideal delivery vector for cancer gene therapy over the past several years. Among the currently developed virus vectors, the adeno-associated virus (AAV) vector is considered as one of those that are closest to the ideal vector mainly for genetic diseases due to the following prominent features; the lack of pathogenicity and toxicity, ability to infect dividing and non-dividing cells of various tissue origins, a very low host immune response and long-term expression. Particularly, the most important attribute of AAV vectors is their safety profile in clinical trials ranging from CF to Parkinson's disease. Although adenovirus and several other oncolytic viruses have been more frequently used to develop cancer gene therapy, AAV also has many critical properties to be exploited for a cancer gene delivery vector. In this review, we will briefly summarize the basic biology of AAV and then mainly focus on recent progresses on AAV vector development and AAV-mediated therapeutic vectors for cancer gene therapy.

Measurement of interaction force between nanoarrayed integrin alphavbeta3 and immobilized vitronectin on the cantilever tip

Protein nanoarrays containing integrin alphavbeta3 or BSA were fabricated on ProLinker-coated Au surface by dip-pen nanolithography (DPN). An atomic force microscope (AFM) tip coated with ProLinker was modified by vitronectin. We measured the interaction force between nanoarrayed integrin alphavbeta3 or BSA and immobilized vitronectin on the cantilever tip by employing tethering-unbinding method. The unbinding force between integrin alphavbeta3 and vitronectin (1087+/-62 pN) was much higher than that of between BSA and vitronectin (643+/-74 pN). These results demonstrate that one can distinguish a specific protein interaction from non-specific interactions by means of force measurement on the molecular interactions between the nanoarrayed protein and its interacting protein on the AFM tip.

A novel way of therapeutic angiogenesis using an adeno-associated virus-mediated angiogenin gene transfer

To develop a novel therapeutic angiogenesis for the treatment of cardiovascular diseases, angiogenin (ANG1) was examined as a potential therapeutic gene. An adeno-associated virus (AAV)-mediated gene delivery system was used to measure the therapeutic efficacy of ANG1. Using a triple co-transfection technique, rAAV-ANG1-GFP, rAAV- VEGF-GFP and rAAV-GFP vectors were produced, which were then used to infect human umbilical vein endothelial cells (HUVECs) in order to evaluate in vitro angiogenic activities. Their protein expressions, tagged with green fluorescent protein (GFP), were monitored by confocal microscopy. The functional activities were measured using wound- healing HUVEC migration assays. The number of migrated cells stimulated by both the expressed ANG1 and the VEGF in rAAV-infected HUVECs increased almost twice the number observed in the expressed GFP control. In vivo angiogenic activities of the expressed ANG1 or VEGF were determined using mouse angiogenesis assays. The angiogenic activities of ANG1 or VEGF expressed in the injected mice were increased by 1.36 and 2.16 times, respectively, compared to those of the expressed GFP control. These results demonstrate that the expressed ANG1 derived from rAAV infection has in vitro and in vivo angiogenic activities and suggest that the rAAV-ANG1 vector is a potential strategy for therapeutic angiogenesis.

Angiogenin-induced protein kinase B/Akt activation is necessary for angiogenesis but is independent of nuclear translocation of angiogenin in HUVE cells

Angiogenin, a potent angiogenic factor, binds to endothelial cells and is endocytosed and rapidly translocated to and concentrated in the nucleolus where it binds to DNA. In this study, we report that angiogenin induces transient phosphorylation of protein kinase B/Akt in cultured human umbilical vein endothelial (HUVE) cells. LY294002 inhibits the angiogenin-induced protein kinase B/Akt activation and also angiogenin-induced cell migration in vitro as well as angiogenesis in chick embryo chorioallantoic membrane in vivo without affecting nuclear translocation of angiogenin in HUVE cells. These results suggest that cross-talk between angiogenin and protein kinase B/Akt signaling pathways is essential for angiogenin-induced angiogenesis in vitro and in vivo, and that angiogenin-induced PKB/Akt activation is independent of nuclear translocation of angiogenin in HUVE cells.

Myoseverin Is a Potential Angiogenesis Inhibitor by Inhibiting Endothelial Cell Function and Endothelial Progenitor Cell Differentiation

Myoseverin, a new microtubule-binding molecule, acts reversibly on myoblast proliferation without the cytotoxic effects displayed by nonpurine-based microtubule-disrupting molecules, like taxol, vinblastine, nocodazole, and the colchicines. In this study, we examined the effects of myoseverin on in vitro function of endothelial cells and endothelial progenitor cell differentiation in order to explore the possibility for the application of myoseverin as a reversible antiangiogenic agent. Myoseverin potently inhibited proliferation of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner with an IC50 of approximately 8 microM. When myoseverin was removed after treatment for 3 days, all the cells pretreated at a concentration range of 2.5-80 microM resumed the cell growth. It also inhibited VEGF-induced HUVEC migration dose dependently. When mononuclear cells (MNCs) isolated from human cord blood were cultured on fibronectin-coated plates for 7 days, myoseverin decreased the number of adherent cells in a dose-dependent manner with IC50 of approximately 9 microM. It also suppressed the development of ac-LDL uptake ability as well as the expression of endothelial lineage markers, KDR, CD31, and vWF. Finally, it inhibited formation of HUVECs or ex vivo cultivated EPCs into capillary-like structure on Matri-gel and in vivo angiogenesis on the chick chorioallantoic membrane. Therefore, these results suggest that myoseverin can be effectively used for the inhibition of new vessel growth by inhibiting endothelial cell function and differentiation of progenitor cells.

Direct binding of recombinant plasminogen kringle 1–3 to angiogenin inhibits angiogenin-induced angiogenesis in the chick embryo CAM

Angiogenin is one of the most potent angiogenesis-inducing proteins. Angiostatin is one of the most potent angiogenesis inhibitors, and it contains the first four kringle domains of plasminogen (K1-4). Recombinant human plasminogen kringle 1-3 (rK1-3) was expressed in Escherichia coli and purified to homogeneity. The binding of t-4-aminomethylcyclohexanecarboxylic acid with the purified kringle 1-3 was determined by changes in intrinsic fluorescence. rK1-3 exhibits comparable ligand-binding properties as native human plasminogen kringle 1-3. The purified rK1-3 inhibits neovascularization in the chick embryo chorioallantoic membrane (CAM) assay. Interaction of angiogenin with rK1-3 was examined by immunological binding assay and surface plasmon resonance kinetic analysis, and the equilibrium dissociation constants for the complex, Kd, are 0.89 and 0.18 microM, respectively. rK1-3 inhibits angiogenin-induced angiogenesis in the chick embryo CAM in a concentration-dependent manner. These results indicate that rK1-3 directly binds to angiogenin and thus rK1-3 inhibits the angiogenic activity of angiogenin.

Protein nanoarray on Prolinker™ surface constructed by atomic force microscopy dip-pen nanolithography for analysis of protein interaction

Protein nanoarrays are addressable ensembles of nano-scale protein domain on solid surfaces. This method can serve as a useful platform for ultraminiaturized bioanalysis. In this study, we investigated single molecular nanopatterning and molecular interaction of proteins that were immobilized on Prolinker surface of gold-coated silicon wafer by using dip-pen nanolithography (DPN) method. Contact force and humidity were optimized at 0.01 nN and 80%, respectively. The domain features of protein nanoarrays were developed at the contact time of 5 s. The optimized conditions for the nanoarray process were applied to create protein nanoarray using integrin alpha(v)beta3 and angiogenin. Constructed protein nanoarrays using integrin alpha(v)beta3 have single molecular monolayer with regular domain shape (height 15 +/- 5 nm). The changed height value due to the single molecular interaction between integrin alpha(v)beta3 and vitronectin was approximately 30 +/- 5 nm on Prolinker surface as measured with atomic force microscopy tip. Taken together, these results suggest that protein nanoarray on Prolinker surface fabricated by well-controlled DPN process can be used to analyze single molecular interaction of protein.

Profiling of differential protein expression in angiogenin-induced HUVECs using antibody-arrayed ProteoChip

ProteoChip has been developed as a novel protein microarray technology. So far it has been applied in new lead screening and molecular diagnostics and we expect its role to grow in the field of biology. Here, we investigated the application of ProteoChip for the study of differential protein expression profiles in angiogenin-induced human umbilical vein endothelial cells (HUVECs). Antibody microarrays constructed by immobilizing 60 distinct antibodies against signal-transducing proteins on ProteoChip base plates were used to analyze the expression pattern of cell-signaling proteins in HUVECs treated with angiogenin. The antibody microarray approach showed that angiogenin induced the up- and down-regulation of several cellular regulators related with cell proliferation. Changes in the expression of signaling proteins determined by antibody microarray were validated by Western blot analysis. In this experiment, ten up-regulated proteins and six down-regulated proteins were identified and confirmed by immunoblot analysis. Taken together, these data suggest that antibody microarrays using ProteoChip technology can be a powerful tool for high-throughput analysis of proteomes in biological samples.

High level production of bovine angiogenin in E. coli by an efficient refolding procedure

Recombinant bovine angiogenin (rbAng) was expressed in E. coli at up to 30% of total cell proteins but was produced as inclusion bodies. By investigating the effect of various factors on the refolding yield, we obtained about 60% refolding. After chromatographic purification, about 60 mg purified angiogenin was obtained from 1 l culture. The purified recombinant bovine angiogenin was identical to native bovine angiogenin (nbAng) obtained from cow's milk. Our approach is highly efficient and can be generally used for the production of various types of angiogenin for functional and structural studies as well as therapeutic purposes.